AbstractFreak waves, also called rogue waves and giant waves, are much larger and steeper than the surrounding waves, can cause severe accidents, and can be formed in both coastal and offshore regions. The past researchers on freak waves in coastal regions are mainly focused on the statistical properties, and the generation mechanism of such large waves are not yet discussed intensively. The aim of the present study is to examine the generation process of freak waves in unidirectional propagating random waves over a submerged bar using a fully nonlinear numerical wave model, SWASH. It was found that freak waves are readily formed at the seaward part of the crest of the bar and gradually emerged from an intense wave group. The enhancement of the bound higher harmonics in the shoaling process is the main reason to form such large waves in shallow water. On the crest bar of the bathymetry, the extreme wave gradually vanished, mainly due to the releasing of bound higher-harmonics to free wave components.
Ducrozet, G., Gouin, M. (2017) Influence of varying bathymetry in rogue wave occurrence within unidirectional and directional sea-states. Journal of Ocean Engineering & Marine Energy (6), 1-16.
Slunyaev, A. et al. (2016): Rogue events in spatiotemporal numerical simulations of unidirectional waves in basins of different depth. Nature Hazards, 84, S549- S565.
Zijlema, M., Stelling, G., Smit, P. (2011) SWASH: An operational public domain code for simulating wave fields and rapidly varied flows in coastal waters. Coastal Engineering, 58(10), 992-1012.